| Furcacauda Temporal range: 453–359 Ma Silurian to Devonian [1] |
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|---|---|
| Furcacauda heintzae | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Subphylum: | Vertebrata |
| Class: | Thelodonti |
| (unranked) | Furcacaudiformes |
| Family: | Furcacaudidae |
| Genus: | Furcacauda |
| Species | |
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Furcacauda heintzae |
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According to the Systema Naturae 2000 Taxonomic classification, Furcacauda is a genus within the family of Furcacaudidae, within the order Thelodonti, the Class Agnatha, and the Subphylum Vertebrata.[2] Canadian fossils give rise to the Furcacaudiformes during the Devonian and Silurian time periods.[2] Furcacaudiformes were deep water jawless vertebrates with symmetrical fork and lobed-finned tails and smaller than typical loganellid and nikoliviid thelodonti scales.[1] Furcacaudiformes are noted to having a laterally compressed body, large anterior eyes, slightly posterior, lateral, and vertical to a small mouth, and a condensed curved row of branchial openings (gills) directly posterior to the eyes.[2] Many but not all had laterally paired fins.[2] Wilson and Caldwell also note the presence of a caudal peduncle and a long caudal fin made of two large lobes, one dorsal and one ventral separated by 8 to 14 smaller intermediate lobes, giving the appearance of a striated half-moon shaped tail[1] resembling the tail of a heterostracan.[2] A large square cavity within the gut connecting a small intestine to an anal opening lead many to believe that it is this genus that exhibits the first vertebrate stomach.[1] According to Wilson and Caldwell their discovery, based on sediment infillings of fossils of the Furcacauda heintze, gives credence to the evolutionary development of stomach before jaws.[1]
3. ^The Taxonomicon. (2004–2009). Retrieved November 6, 2009, from the World Wide Web: http://taxonomicon.taxonomy.nl/TaxonTree.aspx?id=146819